Background
Running waters are continuously exposed to a wide range of different micropollutants, which enter the water bodies via various pathways and can cause adverse effects in exposed organisms even at low concentration levels (ng/l to µg/l range) and impair the entire ecosystem. At least since the last decade, other stressors on aquatic ecosystems have been increasingly identified. Climate change leads to prolonged heat waves and heavy rain events worldwide, which are expected to increase in duration and intensity. Significantly increased proportions of treated effluent from wastewater treatment plants (WWTPs), higher water temperatures, and lower oxygen levels during dry weather periods contrast with high proportions of untreated wastewater due to stormwater overflow basin (SOB) discharges, run-off from agricultural areas, remobilization of pollutants from sediment, particulate loads, and hydraulic stress during heavy rain events.
